Intravascular stent device

ABSTRACT

A very small diameter intravascular stent device which may be used to occlude or partially occlude an aneurysm in the human brain which is comprised of a thin-walled skeletal cylindrical tube formed of undulating or sinusoidal elements which, when compressed, nest tightly with each other.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to intravascular devices for implantationwithin a vessel of the body, and more particularly to a stent devicewhich may be used in the treatment of blood vessel disorders. Morespecifically, the intravascular device may take the form of an aneurysmcover to be used in the treatment of aneurysms which occur in the brain.

[0003] 2. Description of the Prior Art

[0004] On a worldwide basis, nearly one million balloon angioplastieswere performed in 1997 to treat vascular disease, including bloodvessels clogged or narrowed by a lesion or stenosis. The objective ofthis procedure is to increase the inner diameter or cross-sectional areaof the vessel passage, or lumen, through which blood flows.

[0005] Another serious vascular defect is an area of weakened vesselwall that causes a bulge, or bubble, to protrude out in a radialdirection from the vessel. This type of defect is called an aneurysm. Ifuntreated, the aneurysm may continue expanding until it bursts therebycausing hemorrhaging from the vessel.

[0006] In an effort to prevent restenosis or treat an aneurysm withoutrequiring surgery, short flexible cylinders or scaffolds, made of metalor polymers, are often placed into a vessel to maintain or improve bloodflow. Referred to as stents, various types of these devices are widelyused for reinforcing diseased blood vessels, for opening occluded bloodvessels, and for defining an internal lumen to relieve pressure in ananeurysm. The stents allow blood to flow through the vessels at animproved rate while providing the desired lumen opening or structuralintegrity lost by the damaged vessels. Some stents are expanded to theproper size by inflating a balloon catheter, referred to as “balloonexpandable” stents, while others are designed to elastically resistcompression in a “self-expanding” manner.

[0007] Balloon expandable stents and self-expanding stents are generallydelivered in a cylindrical form, crimped to a smaller diameter and areplaced within a vessel using a catheter-based delivery system. Whenpositioned at a desired site within a vessel, these devices are expandedby a balloon, or allowed to “self-expand,” to the desired diameter.

[0008] One such stent for treatment of abdominal aortic aneurysms isdisclosed in U.S. Pat. No. 6,267,783 to Robert P. Letendre, et al. Thispatent discloses a self-expanding stent which may be used in thetreatment of aortic aneurysms. This device may be easily recapturedafter placement and repositioned to a new position within the vessel.This patent, assigned to a related company, is subsequently referred toand the disclosure therein is incorporated and made a part of thesubject patent application.

[0009] Another stent aneurysm treatment device is disclosed in U.S. Pat.No. 6,361,558, assigned to the same assignee as the present application.This patent discloses vasculature stents of various configurations whichmay be used as aneurysm covers for occluding, or partially occluding,aneurysms located at various positions along the blood vessels.

SUMMARY OF THE INVENTION

[0010] There is a need for an improved stent which may be easilydelivered to a vasculature site through a very small catheter, iscapable of being repositioned and which exhibits sufficient structuralintegrity and resilience under radial compressive forces. Moreparticularly, there is a need for such a stent that, in its compressedstate prior to delivery of the stent, has a diameter which is extremelysmall. Such a stent could be placed in a very small microcatheter forsubsequent positioning within a vessel of the human brain. Obviously,such vessels are extremely small and very tortuous throughout theirlength.

[0011] In accordance with one aspect of the present invention, there isprovided a self-expanding stent device which includes a small diameterskeletal tubular member. The skeletal tubular member is comprised of aplurality of cells which are formed by a plurality of generallyundulating members and a plurality of struts. The undulating members aregenerally parallel with the longitudinal axis of the tubular member andare generally parallel to each other. In addition, the undulatingmembers have a plurality of peaks. The undulating members and struts areinterconnected and have a repeating pattern in which the proximal endsof the struts are attached to the peaks of the undulating members andthe distal end of the struts are attached to the peaks of adjacentundulating members.

[0012] In accordance with another aspect of the present invention, theskeletal tubular member has a very small compressed diameter fordelivery within a vessel and a normally biased expanded diameter forretaining the stent against the walls of the vessel. As the tubularmember is compressed to its small diameter, the peaks of the undulatingmembers pull upon the proximal end of the struts and the distal ends ofthe struts pull upon peaks of adjacent undulating members therebycausing the cells of the tubular members to collapse and “nest”together. This nesting causes the skeletal tubular member to retain avery small diameter.

[0013] In accordance with another aspect of the present invention, theskeletal tubular member includes at least two proximal legs which extendgenerally parallel to the longitudinal axis of the tubular member andare attached to the proximal end of the tubular member. At least one ofthe proximal legs includes a T-shaped or I-shaped attachment flange.

[0014] In accordance with still another aspect of the present invention,the proximal legs are biased outwardly from the longitudinal axis of thetubular member. The proximal legs preferably include a radiopaque markerfor positioning the stent within a vessel.

[0015] In accordance with another aspect of the present invention, thetubular member includes at least one distal leg which extends generallyparallel to the longitudinal axis of the tubular member and is attachedto the distal end of the tubular member. The distal leg preferablyincludes a radiopaque marker for locating the distal end of the stent asthe stent is placed in a vessel.

[0016] In accordance with still another aspect of the present invention,there is provided a self-expanding stent device which includes a smalldiameter skeletal tubular member which is formed with a thin wall. Thewall of the tubular member includes a plurality of cells which areformed by a plurality of sinusoidal members and a plurality of struts.The sinusoidal members are generally parallel to the longitudinal axisof the tubular member and are generally parallel to each other. Eachsinusoidal member has a plurality of positive peaks and negative peaks.The sinusoidal members and the struts are interconnected and have arepeating pattern in which each strut connects a positive peak of asinusoidal member with a negative peak of an adjacent sinusoidal member.

[0017] In accordance with still anther aspect of the present invention,the skeletal tubular member has a very small compressed diameter fordelivery within a vessel and a normally biased expanded diameter forretaining the stent device against the walls of a vessel. As the tubularmember is compressed to its small diameter, the positive peaks of thesinusoidal members pull the struts, and the struts pull the negativepeaks of adjacent sinusoidal members thereby causing the cells of thetubular member to collapse with the result that the sinusoidal members“nest” together with adjacent sinusoidal members in order to provide avery small diameter stent device.

[0018] In accordance with still another aspect of the present invention,a self-expanding aneurysm cover is provided which when placed across ananeurysm of a blood vessel reduces, or obstructs, the flow of bloodbetween the aneurysm and its related blood vessel. The aneurysm coverincludes a small diameter skeletal tubular member which is comprised ofa plurality of cells which are formed by a plurality of generallyundulating members and a plurality of struts. The undulating members aregenerally parallel with the longitudinal axis of the tubular member andare generally parallel to each other. In addition, the undulatingmembers have a plurality of peaks. The undulating members and struts areinterconnected and have a repeating pattern in which the proximal endsof the struts are attached to the peaks of the undulating members andthe distal end of the struts are attached to the peaks of adjacentundulating members.

[0019] These and other aspects of the present invention and theadvantages thereof will be more clearly understood from the foregoingdescription in drawings of a preferred embodiment of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is an oblique prospective view of an intravascular stentconstructed in accordance with a preferred embodiment of the presentinvention;

[0021]FIG. 1a is an expanded view of the proximal portion of theretaining legs shown in FIG. 1;

[0022]FIG. 2 is a side elevational view of the intravascular stentillustrated in FIG. 1 with the tubular stent being cut along a line andflattened into a single plane; and,

[0023]FIG. 3 illustrates in more detail the proximal retaining legs ofFIG. 1a and the interconnecting elements between the intravascular stentand a positioning catheter.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024]FIG. 1 illustrates a self-expanding stent device 10 which is lasercut to form a thin-walled, skeletal tubular member 11 comprised ofnickel-titanium alloy. Once cut, the wall 12 of the tubular member 11includes several openings, or cells 14. When the skeletal tubular member11 is placed over an aneurysm, a physician is able to deliver emboliccoils or other such devices through the cells 14 and into the aneurysm.The tubular member 11 also functions to cover the mouth of the aneurysmthus obstructing, or partially obstructing, the flow of blood into theaneurysm. Also, the tubular member 11 prevents medical devices such asembolic coils from escaping the aneurysm.

[0025] The preferred length of the skeletal tubular member 11 may rangefrom 0.0795 inches to 3.15 inches. The diameter of the tubular member 11varies depending on its deployment configuration. In a non-deployed orexpanded state, the diameter of the tubular member 11 may extend up toabout 0.4 inches. When the skeletal tubular member 11 is compressed tofit within the lumen of a deployment catheter, the diameter may bereduce to about 0.014 inches.

[0026] Attached to the proximal end 16 of the skeletal tubular member 11are three proximal legs 18, 18 a, and 18 b that extend longitudinallyfrom the tubular member 11. The proximal legs 18, 18 a, and 18 b arepreferably biased outwardly from the longitudinal axis of the tubularmember 11. This outwardly biased configuration aids in the deploymentsystem as subsequently described.

[0027] T-shaped or I-shaped attachment flanges 20, 20 a, and 20 b areattached to the tips of each proximal leg 18, 18 a, and 18 b. FIG. 1adescribes the T-shaped or I-shaped flanges 20, 20 a, and 20 b in moredetail. Attached to the distal end 21 of the skeletal tubular member 11are two distal legs 22 and 22 a that extend longitudinally away from thetubular member 11.

[0028]FIG. 1a illustrates in detail one of the T-shaped or I-shapedattachment flanges 20 which is also laser cut from the skeletal tubularmember 11 at the proximal end of one of the proximal legs 18. TheT-shaped or I-shaped attachment flange 20 is slightly arched andoriented on the proximal leg 18 such that the arch coincides with thewall 12 of the tubular member 11.

[0029]FIG. 2 illustrates the repetitive cell pattern of the skeletaltubular member 11. The cell pattern may be formed by interconnectedundulating members 24 and struts 26. Each strut 26 has a proximal end 28and a distal end 30. Each undulating member 24 has a proximal end 32, aplurality of peaks 34, and a distal end 36. The proximal end 32 is theleft tip of an undulating member 24. The peaks 34 are the highest andlowest points of an undulating member 24. The distal end 36 is the righttip of an undulating member 24.

[0030] The undulating members 24 and struts 26 are interconnected in away to maximize “nesting” of the undulating members 24 to therebyminimize the compressed diameter of the skeletal tubular member 11during deployment. The proximal end 28 of each strut 26 is attached to apeak 34 of an undulating member 24 and the distal end 30 of the samestrut 26 is attached to a peak 34 of an adjacent undulating member 24.This interconnection of undulating members 24 and struts 26 permits thecells 14 of the skeletal tubular member 11 to collapse and allows thetubular member 11 to attain a compressed diameter.

[0031] The repetitive cell pattern of the skeletal tubular member 11 mayalso be formed by interconnected sinusoidal members 38 and struts 26.Each sinusoidal member 38 has a proximal end 40, a plurality of positivepeaks 42, a plurality of negative peaks 44, and a distal end 45. Theproximal end 40 is the left tip of a sinusoidal member 38. The positivepeaks 42 are the highest points of a sinusoidal member 38. The negativepeaks 44 are the lowest points of a sinusoidal member 38. The distal end45 is the right tip of a sinusoidal member 38.

[0032] The sinusoidal members 38 and struts 26 are interconnected in away to maximize “nesting” of the sinusoidal members 38 therebyminimizing the compressed diameter of the skeletal tubular member 11during deployment. Each strut 26 connects a positive peak 42 of asinusoidal member 38 with a negative peak 44 of an adjacent sinusoidalmember 38. This interconnection of sinusoidal members 38 and struts 26permits the cells 14 of the skeletal tubular member 11 to collapse andallows the tubular member 11 to attain a compressed diameter.

[0033] Also illustrated in FIG. 2 are the proximal legs 18, 18 a, and 18b and the distal legs 22 and 22 a. In the repetitive cell pattern formedby undulating members 24 and struts 26, the proximal legs 18, 18 a, and18 b are connected to the proximal ends 32 of undulating members 24, andthe distal legs 22 and 22 a are connected to the distal ends 36 ofundulating members 24. In the repetitive cell pattern formed bysinusoidal members 38 and struts 26, the proximal legs 18, 18 a, and 18b are connected to the proximal ends 40 of sinusoidal members 38, andthe distal legs 22 and 22 a are connected to the distal ends 45 ofsinusoidal members 38.

[0034] It should be understood that the stent device of the presentinvention may alternatively be coated with an agent, such as heparin orrapamycing, to prevent stenosis or restenosis of the vessel. Examples ofsuch coatings are disclosed in U.S. Pat. Nos. 5,288,711; 5,516,781;5,563,146 and 5,646,160. The disclosures in these patents areincorporated herein by reference.

[0035]FIG. 3 illustrates the deployment system 46 for the stent device10. The deployment system 46 includes an outer sheath 48 which isessentially an elongated tubular member, similar to ordinary guidingcatheters which are well known to those of ordinary skill in the art.The deployment system 46 also includes an inner shaft 50 locatedcoaxially within the outer sheath 48 prior to deployment. The innershaft 50 has a distal end 52 and a proximal end (not shown). The distalend 52 of the shaft 50 has three grooves 54, 54 a, and 54 b disposedthereon. When the deployment system 46 is not fully deployed, the stentdevice 10 is located within the outer sheath 48. The T-shaped orI-shaped attachment flanges 20, 20 a, and 20 b on the proximal legs 18,18 a, and 18 b of the tubular member 11 are set within the grooves 54,54 a, and 54 b of the inner shaft 50, thereby releasably attaching thestent device 10 to the inner shaft 50. This deployment system isdescribed in more detail in U.S. Pat. No. 6,267,783 assigned to the sameassignee as the present patent application. The disclosure in thispatent is incorporated herein by reference and made a part of thepresent patent application.

[0036] A novel system has been disclosed in which a self-expanding stentdevice comprises a laser cut, skeletal tubular member having a pluralityof cells. Although a preferred embodiment of the invention has beendescribed, it is to be understood that various modifications may be madeby those skilled in the art without departing from the scope of theclaims which follow.

That which is claimed is:
 1. A self-expanding stent device comprising: asmall diameter skeletal tubular member having a thin wall and having aproximal end and a distal end; said wall of said tubular membercomprised of a plurality of cells which are formed by a plurality ofgenerally undulating members and a plurality of struts; said undulatingmembers are generally parallel with the longitudinal axis of saidtubular member and are generally parallel to each other; each undulatingmember has a plurality of peaks; each strut has a proximal end and adistal end; said undulating members and said struts are interconnectedand have a repeating pattern in which the proximal ends of said strutsare attached to the peaks of said undulating members and the distal endsof said struts are attached to the peaks of said adjacent undulatingmembers.
 2. A self-expanding stent device as defined in claim 1, inwhich said skeletal tubular member has a small compressed diameter fordelivery within a vessel and a normally biased expanded diameter forretaining said tubular member against the walls of the vessel; when saidskeletal tubular member is compressed to its small diameter the peaks ofsaid undulating members pull upon the proximal ends of said struts, andthe distal ends of said struts pull upon the peaks of adjacentundulating members causing said cells of said tubular member to collapseand thereby causing said tubular member to attain said small diameter.3. A self-expanding stent device as defined in claim 1, wherein saidskeletal tubular member includes a proximal leg; said proximal legextends generally parallel to the longitudinal axis of said tubularmember and is attached to the proximal end of said skeletal tubularmember; the proximal leg includes an attachment flange.
 4. Aself-expanding stent device as defined in claim 3, wherein said proximalleg is biased outwardly from the longitudinal axis of said skeletaltubular member.
 5. A self-expanding stent device as defined in claim 3,wherein said proximal leg includes a radiopaque marker.
 6. Aself-expanding stent device as defined in claim 1, wherein said tubularmember includes at least one distal leg; said distal leg extendsgenerally parallel to the longitudinal axis of said tubular member andis attached to the distal end of said skeletal tubular member.
 7. Aself-expanding stent device as defined in claim 6, wherein said distalleg includes a radiopaque marker.
 8. A self-expanding stent device asdefined in claim 2, wherein said skeletal tubular member is constructedfrom a nickel-titanium alloy.
 9. A self-expanding stent devicecomprising: a small diameter skeletal tubular member having a thin walland having a proximal end and a distal end; said wall of said tubularmember comprised of a plurality of cells which are formed by a pluralityof sinusoidal members and a plurality of struts; said sinusoidal membersare generally parallel to the longitudinal axis of said tubular memberand are generally parallel to each other; each sinusoidal member has aplurality of positive peaks and a plurality of negative peaks; saidsinusoidal members and said struts are interconnected and have arepeating pattern in which each strut connects a positive peak of eachsinusoidal member with a negative peak of each adjacent sinusoidalmember.
 10. A self-expanding stent device as defined in claim 9, inwhich said skeletal tubular member has a small compressed diameter fordelivery within a vessel and a normally biased expanded diameter forretaining said tubular member against the walls of a vessel; when saidskeletal tubular member is compressed to its small diameter the positivepeaks of said sinusoidal members pull upon said struts, and said strutspull upon the negative peaks of adjacent sinusoidal members causing saidcells of said tubular member to collapse and thereby causing saidtubular member to attain said small diameter.
 11. A self-expanding stentdevice as defined in claim 9, wherein said tubular member includes aproximal leg; said proximal leg extends generally parallel to thelongitudinal axis of said tubular member and is attached to the proximalend of said tubular member; the proximal leg includes an attachmentflange.
 12. A self-expanding stent device as defined in claim 11,wherein said proximal leg is biased outwardly from the longitudinal axisof said skeletal tubular member.
 13. A self-expanding stent device asdefined in claim 11, wherein said proximal leg includes a radiopaquemarker.
 14. A self-expanding stent device as defined in claim 9, whereinsaid skeletal tubular member includes at least one distal leg; saiddistal leg extends generally parallel to the longitudinal axis of saidskeletal tubular member and is attached to the distal end of saidtubular member.
 15. A self-expanding stent device as defined in claim14, wherein said distal leg includes a radiopaque marker.
 16. Aself-expanding stent device as defined in claim 10, wherein saidskeletal tubular member is constructed from a nickel-titanium alloy. 17.A self-expanding aneurysm cover comprising: a small diameter skeletaltubular member having a thin wall and having a proximal end and a distalend; said wall of said tubular member comprised of a plurality of cellswhich are formed by a plurality of generally undulating members and aplurality of struts; said undulating members are generally parallel withthe longitudinal axis of said tubular member and are generally parallelto each other; each undulating member has a plurality of peaks; eachstrut has a proximal end and a distal end; said undulating members andsaid struts are interconnected and have a repeating pattern in which theproximal ends of said struts are attached to the peaks of saidundulating members and the distal ends of said struts are attached tothe peaks of said adjacent undulating members.
 18. A self-expandinganeurysm cover as defined in claim 17, in which said skeletal tubularmember has a small compressed diameter for delivery within a vessel anda normally biased expanded diameter for retaining said tubular memberagainst the walls of a vessel; when said skeletal tubular member iscompressed to its small diameter the peaks of said undulating memberspull upon the proximal ends of said struts, and the distal ends of saidstruts pull upon the peaks of adjacent undulating members causing saidcells of said tubular member to collapse and thereby causing saidtubular member to attain said small diameter.
 19. A self-expandinganeurysm cover as defined in claim 17, wherein said skeletal tubularmember includes at least two proximal legs; said proximal legs extendgenerally parallel to the longitudinal axis of said tubular member andare attached to the proximal end of said skeletal tubular member; atleast one proximal leg includes a T-shaped attachment flange.
 20. Aself-expanding aneurysm cover as defined in claim 19, wherein saidproximal legs are biased outwardly from the longitudinal axis of saidskeletal tubular member.
 21. A self-expanding aneurysm cover as definedin claim 19, wherein said proximal legs include a radiopaque marker. 22.A self-expanding aneurysm cover as defined in claim 17, wherein saidtubular member includes at least one distal leg; said distal leg extendsgenerally parallel to the longitudinal axis of said tubular member andis attached to the distal end of said skeletal tubular member.
 23. Aself-expanding aneurysm cover as defined in claim 22, wherein saiddistal leg includes a radiopaque marker.
 24. A self-expanding aneurysmcover as defined in claim 18, wherein said skeletal tubular member isconstructed from a nickel-titanium alloy.